1. Field of Invention
This invention relates to accessories for common 20" box fans, specifically to devices which permit window mounting and operation of such fans, alternatively referred to as portable suitcase fans.
2. Description of Prior Art
Typical box fan usage demonstrates need for the invention, and indicates the high efficiency of window mounted fans. Manufacturers information will be cited. Portable 20" box fans have been extremely popular for at least forty-six years. These large, economical fans are lightweight and capable of moving a lot of air. Innovations to improve the versatility and efficiency of these fans have been limited.
Many home or apartment windowsills are too narrow (front to back) to support a box fan. The fan will simply fall over to the floor. Most box fan feet are spaced from 5.5" to 6.75" apart. Nearly all sills on "horizontal" type sliding windows are too narrow. The (flat) surface is usually less than 4.5" wide. This type of window is predominant in western U.S. homes (especially apartments). They have been popular since the 1950's. Even on wider windowsills the fan may fall to the floor during outdoor wind reversal, so extra security can still be desirable. Most types and sizes of "vertical" sliding sashes can be closed on the fan top regardless of sill width. The fan speed control knob or handle must be leaned against one side of the window sash for reliable support. The fan overhangs into the space under the sash, between the sash track and window screen to permit such use. This is not possible with a "horizontal" sliding sash window, since the sash track and screen are side by side. The sash track and screen track are usually an integral aluminum unit which is raised from the sill surface.
Most portable box fans are operated at night or when outdoor air is cooling. Normally, all the house windows are opened. If the windows will not accommodate the box fan, it is placed on a table, chair, dresser or anything available near a window. This is done to try and exhaust the hot air, and draw in cool air through the other windows. Window placement is especially crucial if there is little wind outdoors. Any large fan sitting in front of a screen door is in the way. This position is usually close enough to the television to be a noise problem. Placing the box fan anywhere except right in a window or other opening does little more than circulate indoor air within one room. Some type of oscillating fan is normally used for this purpose.
Fan capacity specifications from different manufacturers vary greatly, but generally a conventional 20" "window fan" with an extra high speed motor is recommended to ventilate an entire "average" size, two story house. A 20" "window fan" with a standard motor is recommended for an entire single floor. Average cost of this cheeper version is still four to five times the 20" box fan price. U.S. Pat. No. 2,715,495 to Bastian (1950) discloses the basic type of "window fan" mounting. Conventional "window fans" are designed for seasonal, semi-permanent installation, and cannot be readily moved to other windows. These "window fans" are made to be installed only in "vertical" type sliding windows of limited width, 36" to 41" max./27" min. wall-to-wall. Sliding panels on each side of the fan are moved into the window frame track or attached by wood screws to the frame surface. Then, four special screws in the fan housing are tightened to lock the panels in place and support the fan. 20" "window fans" cannot be used in "horizontal" sliding windows since the open half is on one side, therefore, only one fan panel can be extended and will not reach the opposite side wall. The frame track on this type of window cannot be used, since the standard opening is only 21" wide. A conventional "window fan" that will work in "horizontal" type window openings requires such a small inefficient fan size that it defeats the "whole house" ventilating capability.
"Attic fans" are the most effective at removing hot air. They are very expensive and require major ceiling construction work.
"Pedestal fans" work poorly for "whole house" use. They are top heavy, requiring a broad base, which prevents effectively close placement to a window. The largest diameter commonly available is a substantial 18", but the tall pedestal and 38" wide base make it cumbersome to move. Carrying this fan through bedroom doorways and placing it around furniture is a problem. An 18" unit costs about five times more than a 20" box fan.
A four leg, two wheel stand is available for 20" box fans. The combination is awkward to move since the legs are made widely spaced for stability. Getting around furniture is a problem. This combination usually cannot be placed close enough to windows to provide much coupling with outdoor air. The stand costs as much as the box fan itself.
Heretofore most prior art related only to air conditioners and conventional "window fan." If their mounting features were incorporated into a portable box fan, the result would approximate a conventional "window fan" in terms of high cost, inconvenience and limited versatility for use with different window types. New design methods would not benefit box fans that are already in use.
Heretofore the only adapter specially designed for portable box fans was U.S. Pat. No. 5,050,831 to Joyal (1991) disclosing an adapter that is limited to using the fans carrying handle together with a "vertical" sliding window sash. The preceding discussion, on page one of this present specification indicates why an adapter is usually not necessary (though helpful) with "vertical" sliding sash windows. In light of this notation the Joyal disclosure is of moderate value. This restrictive adapter is also rather inconvenient to use. It must be removed from the fan handle to reverse or carry the fan to another window. The window "sash" must be adjusted each time the fan is installed, removed or reversed. The more complex, two piece "adjustable" embodiment would likely be as expensive to manufacture as the box fan itself. The telescoping sash post used for "ventilation adjustment" is generally not needed since virtually all box fans have selectable motor speeds.
U.S. Pat. No. 2,529,040 to Morrison (1950) discloses a semi-permanent type "window fan." Morrison uses common hardware store turnbuckles to tighten his fan against rubber pads located on both sides of a "vertical" sliding window. If the end user of a portable box fan employed turnbuckles for support, he would have to modify and damage the window frame and fan.
The instructions supplied with all box fans specifically warn consumers not to use the fan where curtains may be drawn into the air intake. This may cause motor overheating with possible fire hazard. It should be noted that the use of turnbuckles does not solve this problem. It is often possible to position a standard portable box fan near the face of some window frame types. The small space between the turnbuckle and fan could possibly be used to retain a small, thin curtain made of lace, but could not be used with more common curtains. Such use, even with small lace curtains, would be inconvenient and awkward. The box fan carrying handle encloses a similar size space and is therefore equally impractical for such use.